As a nutritionist, these are questions I hear all the time. The simple answer is that no, sugar doesn’t cause cancer. Of course, the details are a bit more complex than that.

The way eating too much sugar changes our bodies can harm us, and those things increase our risk for a range of diseases in ways we don’t fully understand.

Does sugar feed cancer?

All cells in our body use glucose for energy. Cancer cells use it quicker since they are dividing more rapidly. Sugar, as glucose, feeds our bodies, so if we have cancer, it feeds that, too. However, cutting out artificial sugar won’t starve the cancer cells.

There seems to be a relationship between insulin resistance and cancer. It’s not clear if insulin resistance causes cancer or impacts survival rates, but there does seem to be some sort of connection.

What is exactly is sugar?

Sugar is a type of carbohydrate. The technical definition of a carbohydrate is a molecule that has a molar ratio of carbon to hydrogen to oxygen is 1:2:1. We eat carbohydrates in a number of different foods but it is important to distinguish between simple and complex.

Is sugar simple or complex?

Simple carbohydrates are those that are shorter chained molecules like monosaccharides and disaccharides (glucose, galactose and fructose to name a few). Simple carbohydrates are found in foods like white rice, cookies, and candies. They tend to have sweeter taste and generally cause a larger insulin response with the exception of fructose.

Complex carbohydrates are longer chains and include glycogen, cellulose, pectin, and gums. These tend to have starchier mouth feels and often contain fiber, blunting an insulin response. Complex carbohydrates include whole grains, vegetables, and fruits.

Why do we need sugar?

Maintaining normal glucose levels is critical for cell respiration and sustaining essential functions like brain and muscle function. Even when we deplete our supplies of glucose our bodies will still find alternate pathways to create glucose through metabolism of fats and proteins.

From an evolutionary perspective, we have an innate taste for sugar. Sugar actually causes dopamine to be released in the brain. Sweetness and sugars signal safety and contain quick sources of energy.

The research behind cancer and sugar

Researchers have been investigating several mechanisms that may uncover a potential connection behind sugar and cancer.

AGEing

One of the relationships between sugar and cancer has to do with Advanced Glycation End Products or AGES. AGES are highly unstable molecules. They are linked to oxidation and inflammation, creating unstable cellular environments possibly more conducive to the propagation of cancer cells. We all form AGES as a normal part of aging. However, since simple sugars serve as the backbone of AGE molecules, people who consume more simple sugars in their diets may have higher rates of AGE formation.

Insulin resistance

When a cell is insulin resistant, the insulin transporter does not work to allow insulin to latch onto a cell. Thus, glucose remains in the blood, driving the body to release even more insulin. This is insulin resistance.

Some ways that cancer and sugar may be linked are specific to certain types of cancer.

Breast cancer

In the case of breast cancer, the relationship between sugar and cancer seems to manifest through hormonal changes. There only seems to be a relationship with estrogen receptor-positive breast cancer. Insulin and insulin growth factor-1 (IGF-1) receptors increase sex hormone synthesis and reduce sex hormone binding globulin levels leading to elevated levels of estrogen and other hormones that may contribute to tumor progression. There are also studies that show that once someone has breast cancer, insulin resistance may lead to a worse prognosis.

Pancreatic cancer

It is unknown if insulin resistance causes pancreatic cancer, pancreatic cancer causes insulin resistance or a bit of both. A meta-analysis that included 35 case-control and nested case-control studies from 1966 to 2010 reflected that diabetes increased risk of pancreatic cancer by 2 fold. In addition, an in vitro study using human pancreatic cancer cells showed that a high glucose environment weakened the effects of 5 FU, a common chemotherapy used for the treatment of pancreatic cancer.

Lung, liver, and endometrial cancer

There seems to be a positive but insignificant increased risk between insulin resistance and cancers located in the lung and endometrium. There is a positive risk association between insulin resistance and liver cancer.

What actually causes insulin resistance?

One of the main causes of insulin resistance is visceral adipose tissue (VAT), or the fat that we deposit around our waistlines. VAT produces more markers of inflammation associated with insulin resistance than adipose tissue elsewhere in the body. What causes visceral adipose tissue deposition? Eating to excess in general, not just excess sugar intake.

How can you decrease your cancer risk?

Metformin is a medication typically used to treat type 2 diabetes that may lower cancer risk. It lowers glucose by suppressing glucose production by the liver, increasing insulin sensitivity and opposing the action of insulin. Initial experimental data suggests metformin may exhibit antitumor actions. Talk to your doctor for more information if you think you need help decreasing your cancer risk.

Hillary is a Registered Dietitian and Board Certified Specialist in Oncology Nutrition (CSO). She received her BS in Nutritional Sciences at Cornell University and MS in Clinical Nutrition at New York University, and completed her dietetic internship at the James J. Peters Bronx VA Medical Center. Hillary works as an outpatient dietitian at the North Shore-LIJ’s Cancer Institute, where she counsels patients and their families before, during and after cancer treatment. Additionally, Hillary counsels clients on nutrition through her private practice, Recipe for Health, L.L.C., and has been invited to present at several nutrition-related events including the Breast Cancer Update Symposium at North Shore-LIJ (2013) and Adelphi University’s Farm to Table lecture (2014). Hillary strives to translate the science behind health, nutrition and prevention into practical and easy-to-follow recommendations.